RE: Regression v5.12-rc3: net: stmmac: re-init rx buffers when mac resume back

[Joakim Zhang]

> -----Original Message-----
> From: Jon Hunter <jonathanh@xxxxxxxxxx>
> Sent: 2021年3月30日 20:51
> To: Joakim Zhang <qiangqing.zhang@xxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; Linux Kernel Mailing List
> <linux-kernel@xxxxxxxxxxxxxxx>; linux-tegra <linux-tegra@xxxxxxxxxxxxxxx>;
> Jakub Kicinski <kuba@xxxxxxxxxx>
> Subject: Re: Regression v5.12-rc3: net: stmmac: re-init rx buffers when mac
> resume back
> 
> 
> 
> On 25/03/2021 08:12, Joakim Zhang wrote:
> 
> ...
> 
> >>>>> You mean one of your boards? Does other boards with STMMAC can
> >>>>> work
> >>>> fine?
> >>>>
> >>>> We have two devices with the STMMAC and one works OK and the other
> >> fails.
> >>>> They are different generation of device and so there could be some
> >>>> architectural differences which is causing this to only be seen on one
> device.
> >>> It's really strange, but I also don't know what architectural
> >>> differences could
> >> affect this. Sorry.
> 
> 
> I realised that for the board which fails after this change is made, it has the
> IOMMU enabled. The other board does not at the moment (although work is in
> progress to enable). If I add 'iommu.passthrough=1' to cmdline for the failing
> board, then it works again. So in my case, the problem is linked to the IOMMU
> being enabled.
> 
> Does you platform enable the IOMMU?

Hi Jon,

There is no IOMMU hardware available on our boards. But why IOMMU would affect it during suspend/resume, and no problem in normal mode?

Best Regards,
Joakim Zhang
> Thanks
> Jon
> 
> --
> nvpublic